What spare parts do you keep on hand (excluding another tube)? I’m looking for a spare water pump at the moment. My stock K40 came with a Dymax PH1200 pump which has been working just fine. Every few months I pull it out of the bucket and rinse it out when I also rinse the bucket and add fresh water. Do folks recommend a different pump? Looking on eBay, that one appears to run about $50
Pumps are pretty reliable. Optics are the main expendable. All together, these hold up OK once you’ve got the trouble spots fixed, The Little Giant PE-1 is a good replacement pump.
Yeah, optics is also on my list of things to buy … little by little. I haven’t spend a whole lot of time researching replacement optics yet, but it’s on the short list. Together with an adjustable bed and replacement/upgraded controller.
The only spare parts I keep are materials to laser!!! I just assume that my machine is going to be perfectly good haha. The power of positive thinking!
Yeah, there’s that too … I have a proverbial truckload of wood being delivered tomorrow. Okay, it’s not as much as most, but I also don’t have the storage for a huge quantity, and I can get new shipments delivered within a week, so I just keep an eye on the stock and order when it gets low. 
Right now I’m researching optics … again (I say again because everything I researched a few months ago has been forgotten.) Gotta figure out what’s best, and doesn’t cost an arm and a leg.
Get the 3 mirror set from Saite Cutter on ebay, The Moly ones are good quality and hold up great and the price is quite reasonable. I’ve got a year or so on the only set I’ve had to buy, and they perform like new.
The lenses they sell are also very good, they have a basic lens, and a ‘premium’ with no explanation as to what’s “premium” about them. I’m quite satisfied with the standard ones and I have one in each focal length which adds versatility to the laser.
The air assist head they sell has adjustable focus and makes lens changes a snap. I’d imagine you already have an air assist head, I’ve seen your work and it looks very nice. (If you cut that all with a stock head, you don’t know what you’re missing)
Are the MO mirrors noticeably better than the SI ones? As for air assist, I have my own 3D printed nozzle for a fixed lens. I’m happy with it. With an adjustable bed, it works for me. It keeps the flying head light(er).
The Moly mirrors are harder than the Silicon ones and last much longer.
I have not done any side by side comparisons, except to the stock mirrors (which I believe are Silicon) The stock mirrors degraded just from periodic cleaning (and I know how to treat optics, being a competitive shooter for 30+ years) and it didn’t take too long.
They gradually fell off until you could start to feel a little warmth on the mount after running. I had maybe a couple of months on them. I read up on the subject and found the Moly ones give up a few tenths of a percent in reflectivity to other types, but are the Moly mirrors are the most durable and usually net better performance than the ones with a higher reflectivity index after a few cleanings. I’ve seen zero degradation over the last year or so and the surfaces are still visibly flawless.
I just placed an order for a set for my new laser and paid $24.29 for the set of 3 20mm Moly mirrors from Saite Cutter.
Scott
PS - I haven’t forgotten the photos of my farm equipment miniatures, I pulled them out a couple days ago for my next photo session, which should be soon.
Thanks @Scott_Marshall . Reading the descriptions, it says the MO ones are best suited for 60-100W lasers, while the SI ones are for 40-60W. Being that this is a stock tube that’s also likely being over driven to 40W (from 35, though I have no data on that), would I lose (some) power using the MO ones?
Just for info, it is not reccomended to keep a spare laser tube in stock. They have a shelf life, and by the time you need to reolace your current tube, the spare is probably down to half its life expectancy.
Yeah, that’s why I said ‘excluding tube’ in my post … I’ll get one when I need it …